Mold for making contact lenses

Abstract

To provide a mold assembly for molding a contact lens having an excellent optical performance, which is accomplished by suppressing the axial misalignment brought about by the relative displacement between the male and female molds during the molding operation, the mold assembly has a lens molding cavity ( 30 ) defined therein when the male and female molds ( 1, 2 ) are joined together in an axial direction. A pair of mating faces ( 12, 22 ) are defined in the male and female molds ( 1, 2 ) at locations in the vicinity of outer peripheral edges of molding surface areas ( 11, 21 ) in the male and female molds ( 1, 2 ), respectively. Each face being in the form of an annular face lying substantially parallel to the axial direction. A pair of abutment faces ( 13, 23 ) are positioned radially outwardly of the mating faces ( 12, 22 ) and are, when the male and female molds ( 1, 2 ) are joined together, operable to position the male and female molds ( 1, 2 ) relative to each other in the axial direction.

1 . A mold assembly for use in making a contact lens, which comprises: 
 male and female molds adapted to be joined together in an axial direction, which when they are joined together, a molding cavity complemental in shape to the contact lens is formed;    A pair of mating faces to be mated with each other, each defined in the male and female molds, respectively, at a location in the vicinity of an outer peripheral edge of a molding surface area in the associated male or female mold, and said each being in the form of an annular face lying substantially parallel to the axial direction;    A pair of abutment faces to be abutted to each; each defined in the male and female molds, respectively, at locations radially outwardly of the mating faces and being, when the male and female molds are joined together, operable to position the male and female molds relative to each other in the axial direction.    
     
     
         2 . The mold assembly as claimed in  claim 1 , further comprising a pair of guide faces, each defined in the male and female molds, respectively, at a location radially outwardly of the abutment face, and operable to guide the male and female molds in a mating direction.  
     
     
         3 . The mold assembly as claimed in  claim 1 , further comprising a plurality of anchoring projections formed in one of the male and female molds and a corresponding number of anchoring holes formed in the other of the male and female molds, the anchoring projections, when the male and female molds are joined together, engaging in the corresponding anchoring holes to avoid a relative displacement of the male and female molds in a radial direction generally perpendicular to the axial direction.  
     
     
         4 . The mold assembly as claimed in  claim 1 , which is adapted for molding the contact lens by a thermal polymerization.